Rail bond or the like



March 4, 1947. R SEL QUIST 2,416,883

RAIL BOND 0R LIKE Filed April 5, 1944 2 Sheets-Sheet ,1

INVENTOR March 4, 1947. R. SELQUIST 2,416,833

RAIL BOND OR THE LIKE Filed April 3, 1944 2 Sheets-Sheet 2 J5 ll'iasl'fil'o No. of (yaks-Thousands INVENTORI Po/fSe/gwlsf Patented Mar.4, 1947 RAIL BOND OR THE LIKE Rolf Sc'lquist, McKeesport, Pa., assignorto Cope perweldiSteel Company, Glassport, Pa., av cor poration ofPennsylvania Application April 3, 1944, Serial No. 529,295

2 Claims.

This invention relates to electrical connectors, such as rail bonds, anda method for their manufacture.

One type of rail bond or electrical connector which has been extensivelyused comprises a suitable length of conductor, usually a stranded cableof appropriate size, welded to one or more plugs having tapered shanksand adapted to be driven into holes drilled in the webs of railroadrails. Annealedwire has been used heretofore for the conductor becauseof the necessity for bending the conductor which is shipped straight, tothe desired curvature adjacent the ends when installing it in the field.The necessity for manually shaping the conductor has prevented the useof hard-drawn wire, even though it is stronger than annealed wire, inmaking a bond of the conventional welded type. Bon of h s yp have incertain cases exhibited fatigue failure of the conductor adjacent thehead of the plug. It will be appreciated that, under the conditions ofservice existing on railroads carrying heavy traflic, rail bonds arerepeatedly subjected to severe vibration and impact so that theresistance of a bond to failure by fatigue is one of its most importantqualities. 7

The object of my invention is 'to provide a rail bond or the likehavinga conductor of harddrawn wire throughout and thereforecharacterized by a greater fatigue strength than the bonds includingconductors of annealed wire welded to drive plugs. In a preferredembodiment, my improved bond comprises a suitable length of conductor,preferably stranded, composed of hard-drawn wire, inserted through 'atransverse hole in the head of a drive plug, the conductor being securedto the plug substantially exclusively by the frictional grip of thelatter on the former.

A complete understanding of my novel bond and method of manufacture maybe obtained from the following detailed description which refers to theaccompanying drawings illustratin a preferred embodiment and practice.In the drawings,

Figure 1 is an elevation of a drive plug adapted to receive a conductorto form a bond according to my invention;

Figure 2 is a similar view taken at right angles to Figure 1;

Figure 3 is a partial section through a deforming apparatus adapted tooperate on a plug having a conductor inserted therethrough;

Figure 4 is a partial elevation of a bond after completion of thehead-deforming operation;

' the countersink l5.

Figure 5 is an elevation to enlarged scaleof the bond taken at r ghtangles to Figure 4;

Figure 6 is a partial section also to enlarged scale taken along theplane of lineof Figure 4; and

Figure 7 is a set of curves showing graphically the performance of mybond under fatigue test, as compared with bonds having conductors weldedto the drive plug. I

The'iinproved bond of my invention may best be understood from adescription of the method by which it is manufactured. In the preferredmethod, I provide a drive plug Ill having a head H and a tapered shankT2. The top of the head may conveniently have the form of a sphericalsegment as indicated at l3. A transverse hole H is drilled through thehead on a diameter thereof and i countersunk as at 15.

To attach a conductor to the plugill, I insert a length of suitableconductor it of hard-drawn wire, free from the softening resulting fromannealing, preferably a stranded cable, through the hole I4 until theend of the cable is substantially flush with the end of the holeopposite As shown in Figure 4, the size of the hole [4 is such as toprovide slight clearance for theconductor to facilitate insertion of thelatter. When the conductor has been in-' serted in the hole through thehead of the plug, 1' subject the head to a deforming operation Wherebythe head is caused to obtain a tight frictional grip on the conductor.This peration may conveniently be effected by apparatus such as thatindicated diagrammatically in Figure 3, including a die plate I! restingon a base plate l8 which may be the platen of a press having areciprocable head 19. The die plate ll has a tapered bore 28 thereinadapted to accommodate the shank l2 of the plug in axial alignment withthe head l9.

When the die head l9 of the press is caused to descend with sufficientforce, the head It is deformed by compression or squeezing so that itobtains a tight frictional grip on the conductor. The hole I4 issomewhat contracted and the conductor itself, if stranded, is slightlycompacted. If the die head I!) is plane on the end, the sphericallyshaped top l3 of the head I l is flattened asindicated at 2| in Figure 4which showsone end of a completed bond, the other end being identical.If it is desired that the heads of the plugs retain a rounded top afterdeformation, the die head I9 may be made concave at its end.

Figures 5 and 6 further show the finished bond. The end of the conductoris slightly flattened as a result of the crushing down of the plug headunder the force of the press, as shown in Figure 5. The interior of thehole I is slightly indented by the strands of the conductor, as shown inFigure 6,. if the head of the plug is sufificiently deformed. This isdesirable since it improves the frictional grip of the head on theconductor, lessening the chance that the conductor will be pulled out ofthe hole in service. The countersink I5 is an important feature in thatit elimithe plug. A further advantage is that my im- 1 actly the samemanner as Til proved bond may be applied to the rail in exused.

It will .be apparent that, while the invention has been described withparticular reference to bonds,

it is also useful in connectors which have a drive plug at one end onlyof the conductor.

nates the sharp edge of the hole which might otherwise nick or notch thestrands of the conductor under severe vibration in service, whichAlthough I have illustrated anddescribed but a. preferred embodiment andpractice of my invention,

it will be understood that changes in the design of the parts or in themanufacturing prowouldreduce the fatigue resistance of the bond,v

7 It also prevents the applicationof compressive stress to the conductorwhere it leaves the head,

which would otherwise result in a region oflocalized stressconcentration further tending to reduce the fatigue resistance.

Figure 7 shows graphically the comparison between my-improved'bond andthe welded bond under fatigue test. In this test, samples were subjectedto repeated bending of the conductor in opposite directions throughsmall angles while the plug was held firmly fixed. Curve A is drawnthrough the experimental points designated by dots, obtained in tests ofwelded bonds. Curve B is. drawn through experimental points indicated bycircles, obtained from tests on the bond of my invention. It will bereadily apparent that my bond exhibits considerably higher endurancespirit ofthe invention or pended claims.

cedure may be made without departing from the the scope of the ap- .Iclaim:

1. A rail bond comprising a pair of drive plugs and a length ofconductor, said conductor being composed of hard-drawn wire and havingits ends 1 extending into said plugs, respectively, and secured thereinby affrictional grip, wherebythe conductor is left in its originalhard-drawn state and remains free from thesoftening resulting fromannealing, at least in the portions thereof adjacent the plugs, and istherefore more resistant to fatigue failure under the repeatedvibrationto which it is subjected-in service'th'an a bond having a conductorwhich has been anunder fatigue test than the welded bond. That is tosay, for the ame angle of bend, my bond withstood a great many morerepeated cycles of bendin than the welded bond or, for the same 1numberof bends, my bond could bebent through a considerably greaterangle than the welded bond. This increased'endurance results from theuse of hard-drawn wire forthe conductor and a method of attaching it tothe plugs which does not involve heating the'wireto a temperature abovethe critical point, leaving the wire in its original hard-drawn statethroughout.

My invention is also characterized by further 1 j advantages. In thefirst place, the cost is lower than that of the welded bond since thedeformation of the headof the drive plug is a less expensive operationthan the welding of the conductor to the head. My bond has a totalresistance substantially the same as that of the welded bond. My bond isalso characterized by ample resistance to'pulling out of theoonductorfrom healed at the points of connection to the plugs. 2. A railbond comprising a length of conductor with a drive plug at each endthereof, the ends of the conductor extending into holes in the plugs,respectively, and secured therein by a frictional grip, said holes beingcountersunk at. the

ends into which the conductor extends, thereby preventing localizedstress concentrations at the point where the conductor enters the plugs,

' ROLF SELQUIST:

' REFERENCES CITED '7 e The following references areof record in thefile of thispatent: Y

the bonds previously PATENTS] 1

